It does apply to every lift apart from those designed to be used and have safety back up, the lift shafts have a higher fire regs etc.
When giving out a safety certificate worse case situations are used. If the authorities get a bomb warning (let's face it that's a possibility) then there is a...
Designated stewards to assist evacuation down steps (reserved for such emergencies) maybe.
https://www.stannahlifts.co.uk/products/passenger-lifts/fire-fighting-evacuation
Or special lifts.
Very good but a slight caveat the reason given for not using the lifts are in the case of emergency. Only those capable of using stairs to WSU are supposed to be there. I doubt this is Barber's decision but that of the authorities in the giving of the safety certificate.